Not a silly question Joshua. I'd say most of us have both guides. Sometimes one book will provide information that the other doesn't. At the end of the day both books rate the same for providing us collectors with the stuff we need to know. Of course, the Chip Rack (TCR) is Nevada only. The cost of these works is certainly offset by the value each provide the hobby. Lots of valuable information for those starting out but we all gain something from these value guides as we make our way in the hobby. Neat thing about this hobby is that we find stuff out all the time, take some info from the US Chip Price Guide, compare it to the The Chip Rack, and add in comments you'll find here or elsewhere and a complete picture forms.
I guess the feeling is that a new edition of The Chip Rack, #11, may be due around convention time? Stay tuned here Joshua.